AskDefine | Define quench

Dictionary Definition

quench

Verb

1 satisfy (thirst); "The cold water quenched his thirst" [syn: slake, allay, assuage]
2 put out, as of fires, flames, or lights; "Too big to be extinguished at once, the forest fires at best could be contained"; "quench the flames"; "snuff out the candles" [syn: snuff out, blow out, extinguish] [ant: ignite]
3 electronics: suppress (sparking) when the current is cut off in an inductive circuit, or suppress (an oscillation or discharge) in a component or device
4 suppress or crush completely; "squelch any sign of dissent"; "quench a rebellion" [syn: squelch, quell]
5 reduce the degree of (luminescence or phosphorescence) in (excited molecules or a material) by adding a suitable substance
6 cool by plunging into cold water; "quench metal"

User Contributed Dictionary

English

Pronunciation

  • /kwɛnʃ/
  • /kwEnS/

Verb

  1. To satisfy, especially an actual or figurative thirst.
    The library quenched her thirst for knowledge.
  2. To extinguish or put out (as a fire or light.)
    Then the MacManus went down. The sudden quench of the white light was how I knew it. -- Saul Bellow
  3. To cool rapidly by dipping into a bath of coolant, as a blacksmith quenching hot iron.
    The swordsmith quenched the sword in an oil bath so that it wouldn't shatter.

Translations

satisfy thirst
extinguish a flame
cool rapidly by immersion

Extensive Definition

For other uses, see Quenching (disambiguation)
A quench refers to a rapid cooling. In polymer chemistry and materials science, quenching is used to prevent low-temperature processes such as phase transformations from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and kinetically accessible. For instance, it can reduce crystallinity and thereby increase toughness of both alloys and plastics (produced through polymerization).
In metallurgy, it is most commonly used to harden steel by introducing martensite, in which case the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable. In steel alloyed with metals such as nickel and manganese, the eutectoid temperature becomes much lower, but the kinetic barriers to phase transformation remain the same. This allows quenching to start at a lower temperature, making the process much easier. High speed steel also has added tungsten, which serves to raise kinetic barriers and give the illusion that the material has been cooled more rapidly than it really has. Even cooling such alloys slowly in air has most of the desired effects of quenching.
Extremely rapid cooling can prevent the formation of all crystal structure, resulting in amorphous metal or "metallic glass".
When an electrical current is flowing through a cryogenic superconductor, a slight temperature rise can cause a loss of superconductivity, which leads to resistive heating and a sudden temperature rise. This phenomenon is also called "quenching"

Role of quenching in scrubbing

In pollution scrubbers, sometimes hot exhaust gas is quenched, or cooled by water sprays, before entering the scrubber proper. Hot gases (those above ambient temperature) are often cooled to near the saturation level.
If not cooled, the hot gas stream can evaporate a large portion of the scrubbing liquor, adversely affecting collection efficiency and damaging scrubber internal parts. If the gases entering the scrubber are too hot, some liquid droplets may evaporate before they have a chance to contact pollutants in the exhaust stream, and others may evaporate after contact, causing captured particles to become reentrained. In some cases, quenching can actually save money.
Cooling the gases reduces the temperature and, therefore, the volume of gases,permitting the use of less expensive construction materials and a smaller scrubber vessel and fan.
A quenching system can be as simple as spraying liquid into the duct just preceding the main scrubbing vessel, or it can be a separate chamber (or tower) with its own spray system identical to a spray tower.
Quenchers are designed using the same principles as scrubbers. Increasing the gas-liquid contact in them increases their operational efficiency. Small liquid droplets cool the exhaust stream more quickly than large droplets because they evaporate more easily. Therefore, less liquid is required. However, in most scrubbing systems, approximately one-and-a-half to two and- a-half times the theoretical evaporation demand is required to ensure proper cooling (Industrial Gas Cleaning Institute 1975). Evaporation also depends on time; it does not occur instantaneously.
Therefore, the quencher should be sized to allow for an adequate exhaust stream residence time. Normal residence times range from 0.15 to 0.25 seconds for gases under 540°C (1000°F) to 0.2 to 0.3 seconds for gases hotter than 540°C (Schifftner 1979).
Quenching with recirculated scrubber liquor could potentially reduce overall scrubber performance, since recycled liquid usually contains a high level of suspended and dissolved solids. As the liquid droplets evaporate, these solids could become reentrained in the exhaust gas stream. To help reduce this problem, clean makeup water can be added directly to the quench system rather than adding all makeup water to a common sump.

References

quench in German: Quenching
quench in Modern Greek (1453-): Βαφή (μεταλλουργία)
quench in Spanish: Templado del acero
quench in Persian: کوئنچ
quench in French: Trempe
quench in Italian: Tempra
quench in Japanese: 焼入れ
quench in Polish: Hartowanie (obróbka cieplna stopów żelaza)
quench in Portuguese: Têmpera (metalurgia)
quench in Chinese: 淬火

Synonyms, Antonyms and Related Words

allay, appease, asphyxiate, assuage, blow out, blunt, bottle up, censor, chill, choke, choke off, clamp down on, cool, cork, cork up, crack down on, crush, damp, damp down, dampen, deflect, destroy, deter, disaffect, discourage, disincline, disinterest, distract, divert, douse, drown, extinguish, feast, feed, gag, gratify, hold down, indispose, jump on, keep down, keep under, kill, muzzle, out, overcome, pour water on, put, put down, put off, put out, quash, quell, reduce, regale, repel, repress, sate, satiate, satisfy, shut down on, silence, sit down on, sit on, slack, slake, smash, smother, snuff, snuff out, squash, squelch, stamp out, stanch, stifle, strangle, stultify, subdue, suffocate, suppress, surfeit, throttle, trample out, trample underfoot, turn aside, turn away, turn from, turn off, wean from
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